1. Field of the Invention
This invention relates to the field of drainage of gas and fluid from a body cavity, and, for example, applies to problems associated with draining a chest cavity.
2. Description of the Related Art
When a mammalian chest cavity contains gas and/or fluid, a lung cannot function normally. One way to relieve this problem is to evacuate the problematic gas and/or fluid by a drainage system. Also, in certain procedures such as, for example, open heart surgery, accumulating blood needs to be drained before it clots to avoid complications.
Body cavity drainage systems typically consist of a tubular structure, either round or square or any other shape, made of resilient polymer such as polyvinyl chloride, silicone rubber, polyurethane, etc. and other components including or directing a vacuum source. The vacuum source can be satisfied a number of ways, including a centrally installed vacuum line as found in the majority of medical facilities, a portable vacuum pump providing vacuum generated by an electrical motor and pump, or a self-expanding spring-loaded blood evacuation device. A portable vacuum pump may be configured in accordance with the Portable Modular Chest Drainage System of U.S. Pat. No. 6,352,525 B1.
Traditionally, according to well-known techniques, a flexible tube made of polymer is inserted into the body cavity and connected to a body drainage device to remove gas and/or fluid. Many different sizes of drainage tubes are available, including those ranging from 8 F to 41 F. Existing chest drainage devices are similar in design and typically include a fluid collection reservoir, a bubble chamber to indicate gas leaks from the chest cavity, and a water column to regulate vacuum pressure and prevent influx of atmospheric air in case vacuum pressure is lost from the drainage system. In some units, a water column is replaced with a pressure gauge.
Existing chest drainage systems conventionally use a low vacuum pressure. In such systems, the vacuum pressure applied to the chest tube is normally −20 cmH20 (=14.7 torr) or less. A dry unit with a pressure gauge may use higher pressure, but only slightly higher.
In order to function adequately at conventional vacuum pressure, a large chest tube is necessary. In most existing systems, in order to increase suction area of the tube, side holes, two to six in number, are created. A large chest tube will cause pain at the entry site, increase the chance of would infection and may compress the lung or heart. While a small bore tube may be better tolerated by a patient, a small bore tube may not function adequately at conventional vacuum pressure, and the widely recognized dangers associated with the use of higher vacuum pressures, including damage to body tissue, have discouraged the use of high vacuum pressure to activate small bore drainage tubes.
Thus, there is presently a need for a system and method for increasing drainage efficiency while avoiding the risk of damage to body tissue.